One example of DNA testing is checking that a burger comes from Aberdeen Angus beef.

BBC: Horsemeat scandal: How often does food fraud happen?

In the UK, three Aldi burger products - frozen Oakhurst 100% beef quarterpounders, frozen specially-selected Aberdeen Angus quarterpounders and frozen Oakhurst beefburgers (16 pack) - were withdrawn when the horsemeat discovery was made public.

BBC: Horsemeat row: Aldi is latest to drop Silvercrest